Unwanted Home Visitors

Unwanted Home VisitorsBy Beth Berlin, University of Minnesota Extension

ST. CLOUD, Minn. (9/3/14) —Fall, to many, is a beautiful time of year as the number of mosquitos and gnats decrease, however homeowners find unwanted bugs in or around their home. The boxelder bugs begin to gather outside of some homes in large numbers. Another unwanted guest that congregates in and around the home are the Asian Beetles. The Asian beetles are the multi-colored beetles often mistakenly called lady bugs. Both of these insects are seeking out a site to overwinter, and unfortunately many of them find their way into the home. These home invaders do not feed or reproduce in the home, but are definitely an annoyance.

Boxelder bugs are easily identified by their black and deep-orange/bright-red colors; their wings lay flat on their bodies. The adult boxelder bugs are capable of flying several blocks and sometimes may even fly further than that. The boxelder bugs like sunny areas and are attracted to buildings with a lot of southern exposure. As weather cools, these insects will push into cracks and enter houses near the foundations. Many crawl under shingles and get into wall voids and attics. They also may enter through doors, windows, vent openings and other accessible areas.

Populations of the boxelder bug vary each year and in each area. Environmental conditions often play a role in population numbers, such as warm, dry summers seem to lead to larger populations of boxelder bugs. The life cycle of this bug consists of reproducing and feeding on boxelder, maple, and ash trees. During late summer and fall, boxelder bugs begin leaving the trees to find protected areas for the winter.

The multi-colored Asian lady beetles have been a nuisance and annoyance for many years. Initially introduced to be a biological control of aphids, populations appear to be more concentrated near agricultural fields. Unlike the common lady beetle, or ladybug, the multi-colored Asian lady beetles like to overwinter in large numbers in and around buildings. Another advantage the Asian beetle has is once inside the home they emit a chemical to attract others, which can lead to hundreds if not thousands of unwanted visitors. Sometime their presence isn’t discovered until the following spring when temperatures begin to warm up, though entry occurred the previous fall.

Effective control begins outdoors. Carefully inspect and then seal up any potential entry points with caulk, sealant, or screening. Both insects need only a very small opening to enter the home, so it is important to check all possible entry points and take the time to seal them up.

If populations are too great for your level of tolerance, residual insecticide can be used. Carefully read and follow all product directions before using around the exterior of the home. Because the insects tend to like the warm, sunny conditions focus your efforts on the south and west sides of your home. The best time to spray is when you first observe the insects clustering around the outside of your home or other building before they begin finding entry points. Effective insecticides that are available to the public include bifenthrin, cyfluthrin, cyhalothrin, deltramethrin, permethrin and tralomethrin. There are many trade names for these chemicals, simply read the “Active Ingredients” on the label.

Another option to control boxelder bugs with some effect is using a soap mixture. Mix 1/2 cup of a liquid laundry detergent in a gallon of water in a hand sprayer or squirt bottle. It is important to test this mixture first on an inconspicuous spot before applying it to the entire area, this will ensure the product won’t stain or discolor your home. Apply a coarse spray directly on the bugs as often as necessary. It is important to note that the soap mixture affects only those boxelder bugs that are sprayed and does not prevent other bugs from returning to the site. Soap mixtures are not effective in controlling multi-colored Asian lady beetles.

Unfortunately once these pests get inside, the only practical control is to remove them by hand or with a vacuum cleaner. The use of insecticides indoors is not effective and is not recommended.